This invention relates to a process for depositing metal-containing layers which have a high specific electrical conductivity, involving the decomposition of organometallic compounds in a hydrogen-containing gas or vapor phase by means of a plasma.
It is known to modify substrates by surface coating in such a way that their surfaces have defined functional properties. For example, it is possible to apply specular metal layers to substrates, layers which conduct electrical currents, layers which harden the surface of the substrate /r protect it against wear, layers which improve the adhesion of further layers, etc. The deposition of layers which contain, for example, copper in metallic form makes it possible to produce conductor tracks conductive to electrical currents on non-conducting substrates, for example on ceramic or organic polymers.
It is possible to deposit thin metal layers, for example, by known CVD processes which involve evaporation of organometallic compounds. The decomposition with the formation of metal-containing layers can be effected, for example, thermally or by plasma induction. A plasma-enhanced CVD process (PECVD process) for depositing copper is described by N. Awaya and Y. Arita in Jap. J. Appl. Phys. 30 (1919), pages 1813 to 1817. This involved the introduction and decomposition of copper acetylacetonate in a parallel-plate plasma reactor. The deposited copper layers were studied with respect to their conductivity. It was found that the lowest resistivity of the copper layers occurred at a substrate temperature between 200.degree. C. and 280.degree. C. At deposition temperatures below 100.degree. C., the resistance was so high that it could not be measured.